Is it permissible to sell the father's inheritance of a property registered in the brothers' names, without the permission of their sisters, knowing that the sales contract does not include the sisters' names?

We understand that the property was purchased for all children, males and females, and that the sale occurred without the daughters' permission, even though the property is registered in the names of the male children only.

If that is the case, then the property cannot be sold except with the daughters' consent and permission, because they have ownership in it. One of the conditions for a valid sale is that the seller must be authorized to dispose of the property, or be given permission to sell it, as Al-Bahuti said: "That the sold item be fully owned by its seller at the time of the contract... or that he be authorized to sell it."

If a person sells someone else's property (an unauthorized sale), scholars have differed on its validity. The correct view is that it depends on the approval of the owner of the money. If the owner approves the sale, it is valid and effective. If they annul it, the contract is revoked. This is the view of Abu Hanifa and Malik, and it is supported by the hadith (definition) of Urwah al-Bariqi, may Allah be pleased with him.

Accordingly, if your sisters agree to the sale, it is valid. If they do not agree, the sale must be revoked if possible. Otherwise, you have encroached upon their right, and it is incumbent upon you to appease them and compensate them.

As for a contract conforming to official papers without conforming to Islamic law, this does not make it permissible; Islamic law is the ruling authority, and acting according to administrative regulations is permissible on condition that it does not contravene the provisions of Islamic law.